A little girl snatched off the street near her California home in 1991 has surfaced alive after being forced to live for 18 years in a warren of creepy shacks behind the home of her kidnapper — a convicted rapist who fathered her two children, authorities said yesterday.

Jaycee Lee Dugard, now 29, was 11 when she was grabbed from a bus stop on her way to school by Phillip and Nancy Garrido outside her home in Meyers, near Lake Tahoe, on June 10, 1991. She hadn’t been seen since.

The twisted couple took her to their compound in Antioch, Calif., where she was forced to live for nearly two decades in sheds hidden behind the house, authorities said.

There, Phillip, a 58-year-old registered sex offender, allegedly forced himself on Dugard, impregnating her with two daughters, now 11 and 15.

The three were never allowed to leave their hovels, authorities said.

“They went directly to that property from the kidnapping and she has lived there ever since. The children were born there and have lived there their whole lives,” said El Dorado County Undersheriff Fred Kollar.

“None of the children had ever gone to school, they had never been to a doctor. They had been kept in complete isolation in this compound — if you will — behind the house.”

At no time did Dugard try to escape. “There are no known attempts by her to reach out to anybody,” Kollar said.

In interviews on NBC, ABC and CBS Friday morning, Probyn said the most surprising thing to his wife was that Jaycee looks very young, almost like she did when she taken.

Probyn also said Dugard felt terribly guilty for bonding with her captor.

Garrido and his wife were arrested for investigation of kidnapping and conspiracy.

Phillip was also being held for investigation of rape by force, lewd and lascivious acts with a minor, and sexual penetration.

“And you’re going to find the most powerful story coming from the witness, the victim.”

Garrido’s brother Ron, 65, told The San Francisco Chronicle he was stunned by the allegations but thinks they are plausible.

“I know my brother and I can believe he did that. … He’s a fruitcake,” he said.

The shocking case first came to light Tuesday, when campus police at the University of California, Berkeley stopped Garrido and the two young girls as they tried to hand out religious literature to students.

The officers — sensing that the relationship between Garrido and the children was suspicious — told him they would have to run a background check on him before he could be allowed to hand out pamphlets.

When they did, they discovered he was a sex offender.

In the 1970s, he was convicted of kidnapping and raping a 25-year-old woman he grabbed from a South Lake Tahoe parking lot. He handcuffed her, tied down and held her in a mini-warehouse in Reno, according to news accounts.

Upon learning of his past, the officers immediately contacted his parole officer, who summoned Garrido for a meeting.

When he arrived at a police station in Concord, Calif., Wednesday, he brought his wife, the two youngsters and an adult woman he introduced as Allissa, but who apparently was Jaycee.

“The parole officer was surprised, as he had never seen these individuals in his visits to his house,” Kollar said.

Following intensive questioning, Garrido revealed that he and his wife had kidnapped Dugard.

“These people had information that only the kidnappers would know,” Kollar said. Further questioning convinced investigators they had found the girl who had vanished so long ago.

“We’re 99 percent sure it’s her,” said Lt. Les Lovell, of the El Dorado Sheriff’s Department, who was a detective on the original kidnapping investigation. DNA tests are being conducted.

At first, she didn’t believe what she was being told, and the FBI agent then asked, “Do you want to talk to Jaycee?” said Dugard’s stepfather, Carl Probyn, from whom Terry is separated.

“She called me a bit later and asked, ‘Are you sitting down? They found Jaycee. She is alive,’ ” Carl said. “I’m just numb. I never in a million years thought this would happen.”

Terry raced to Northern California to be reunited with her daughter.

“When [Terry] started to describe how horrible the conditions have been for Jaycee the past 18 years, I had to stop her,” Probyn said. “From what she said, it sounds like she is still 11 years old. I can’t even visualize surviving this.”

Investigators were hard-pressed to describe the elaborate complex of sheds in which the Garridos had hidden Dugard and her kids.

“Try to imagine at the end of the back yard there is a 6-foot fence with tall trees up against it, a dishwasher and garbage cans up against it,” Kollar said.

“And only through an opening in a tarp over that fence would you be able to access that area.

“It was not visible from either adjoining property, and was very unusual in its design.”

Kollar said some of the sheds had been soundproofed and outfitted with electricity and a basic outdoor latrine and shower.

The case has eerie similarities to that of Josef Fritzl, an Austrian who locked up and raped his daughter over 24 years, fathering seven children with her and causing the death of an infant son.

Most of Garrido’s neighbors said they were unaware the girls were living there. But some said they knew Garrido was a registered sex offender, and said he often wandered the area handing out religious tracts and quoting the Bible.

Others claimed they called cops about two years ago to report that there were tents on Garrido’s property and children at the home, despite his sex-offender status. They said nothing ever came of the calls, The Sacramento Bee reported on its Web site last night.

“He had little girls and women living in that backyard, and they all looked kind of the same,” Pratt said. “They never talked, and they kept to themselves.”

She called police, but they couldn’t investigate because they didn’t have a warrant, Pratt said.

Neighbor Diane Doty said she could see the tents and often heard children playing in the backyard, the corner of which abuts her own backyard. She said she even suspected the children lived in the tents, but her husband said she should leave the family alone.

“I asked my husband, ‘Why is he living in tents?'” she said. “And he said, ‘Maybe that is how they like to live.'”